The syllable is a unit of organisation in phonology, the system responsible for the patterns of sounds and signs in language. Typically, a syllable consists of a vowel and at least one consonant, though various combinations are possible, including single vowels. The number and type of syllables in a word, phrase or sentence may strongly influence stress and intonation throughout.
In linguistics, the existence of syllables as organisers of speech sounds and sign language movements is typically used to explain observations about what is possible in language, from native speakers’ perceptions of how many 'beats' there are in a word to the possible ordering of segments such as c, a and t in cat: why English speakers 'feel' there are two syllables in mother but only one in fire, and why *nxalr is not a possible word in English and, indeed, most languages.
The existence of the syllable as an abstract phonological unit that limits the possible sequences of segments is not uncontroversial, and its use in mainstream linguistics literature has been inconsistent. Theories predating the arrival of the currently-mainstream generative phonology, as well as more recent approaches from within generativism itself, have called into question or even outright rejected the syllable in favour of other behavioural explanations from within both phonology and phonetics.